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KVM: X86: fix lazy allocation of rmaps 

If allocation of rmaps fails, but some of the pointers have already been written,
those pointers can be cleaned up when the memslot is freed, or even reused later
for another attempt at allocating the rmaps.  Therefore there is no need to
WARN, as done for example in memslot_rmap_alloc, but the allocation *must* be
skipped lest KVM will overwrite the previous pointer and will indeed leak memory.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Paolo Bonzini 2021-10-15 13:05:00 -04:00
parent e2b6d941ec
commit fa13843d15
1 changed files with 2 additions and 1 deletions
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3
arch/x86/kvm/x86.c
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@ -11392,7 +11392,8 @@ static int memslot_rmap_alloc(struct kvm_memory_slot *slot,
int level = i + 1; int level = i + 1;
int lpages = __kvm_mmu_slot_lpages(slot, npages, level); int lpages = __kvm_mmu_slot_lpages(slot, npages, level);
WARN_ON(slot->arch.rmap[i]); if (slot->arch.rmap[i])
continue;
slot->arch.rmap[i] = kvcalloc(lpages, sz, GFP_KERNEL_ACCOUNT); slot->arch.rmap[i] = kvcalloc(lpages, sz, GFP_KERNEL_ACCOUNT);
if (!slot->arch.rmap[i]) { if (!slot->arch.rmap[i]) {